title: Torque teno virus: its prevalence and isotypes in North India.
abstract: OBJECTIVE
  To investigate the prevalence and genotype distribution of Torque teno virus (TTV) in patients with different liver diseases and chronic renal failure treated at a referral hospital in North India.
  
  
  METHODS
  Whereas prevalence of TTV was based on amplification of conserved region of ORF2 of TTV genome, the genotyping of TTV was carried out using restriction fragment length polymorphism (RFLP) procedure on the N22 region of ORF1.
  
  
  RESULTS
  TTV-DNA was detected in 137 of 513 (26.7%) patients with liver diseases and 38 of 65 (58.5%) patients with chronic renal failure. TTV was also detected in 27% of healthy controls. The sequence analysis of the PCR product from 10 randomly selected cases failed to show a significant sequence divergence when compared with that of the TRM1 isolate of TTV genotype 1. The results of genotyping in 55 randomly selected patients showed the presence of genotype 1 (G1) in 53 (96.4%) and genotype 2 (G2) in 2 cases (3.6%), respectively. Other genotypes were not identified in this patient subgroup, suggesting that G1 is predominant in this area. The results of genotyping by RFLP were also supported by phylogenetic tree analysis, where G1 was found to be the major genotype.
  
  
  CONCLUSIONS
  These results indicate that TTV is moderately present in Indian patients, with G1 to be the major genotype in North India. The pathogenicity and etiological role of TTV in different diseases is still a question mark and warrant further studies.
authors.affiliation: Department of Laboratory Medicine, All India Institute of Medical Sciences, New Delhi-110029, India. drirshad54@yahoo.com
authors.forename: Mohammad
authors.initials: M
authors.lastname: Irshad
authors.forename: Shiwani
authors.initials: S
authors.lastname: Singh
authors.forename: Khushboo
authors.initials: K
authors.lastname: Irshad
authors.forename: Sanjay-Kumar
authors.initials: SK
authors.lastname: Agarwal
authors.forename: Yogendra-Kumar
authors.initials: YK
authors.lastname: Joshi
mesh_terms: D000328:Adult; D000368:Aged; D001483:Base Sequence; D004266:DNA Virus Infections / Q000453:epidemiology* / Q000235:genetics*; D004279:DNA, Viral / Q000235:genetics; D005260:Female; D005838:Genotype; D006801:Humans; D007194:India / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010802:Phylogeny; D015995:Prevalence; D022783:Torque teno virus / Q000235:genetics*
chemical_list: D004279:DNA, Viral